This invention relates to microprocessor controllers and, more particularly, to such controllers as employed in the control of real-time machine operations such as in mail piece processing systems.
It is known to use microprocessor controller for the real-time control of certain machine operations. However, such controllers have not performed most suitably when employed as a over-all system controller for real-time machine operations in such machine environments where a plurality of machine subsystems function in a high speed synchronous and inter-dependent manner.
For example, a mail processing system may be comprised of a envelope feeder mechanism for receiving a stack of envelopes and, in a seriatim manner, serving up the envelope to a sealer-transport mechanism. The sealer-transport mechanism is charged with the function of sealing each envelope as it is caused to traverse a sealing apparatus and to serve-up the envelope to a mailing machine. It is known to also employ a scale mechanism interposed between the sealer-transport mechanism and the mailing machine. The scale mechanism is charged with the function of weighing the envelope by means of a scale, and determining the required postage value and communicating the postage value to a postage meter. In similar manner, a transport mechanism, customarily integral to the scale mechanism, must assume physical control over the envelope for positioning the envelope on the scale and thereafter serve-up the envelope to the mailing machine.
Generally, the mailing machine will include a transport mechanism which assumes control over the envelope and delivers the envelope to a printing station whereupon a postage meter will print an postage indicia on the envelope. The mailing machine transport mechanism will again assume control over the envelope and eject the envelope from the mailing machine.
As aforenoted, in the afore-described mail processing system, envelopes are processed in a seriatim manner. In such mail processing systems, it is known to provide each of the cited mechanisms with a motor or plurality of motors to act as prime movers for the associated mechanisms. As is known, each motor or group of motors is under the control of a microprocessor motor controller acting through respective driver boards. It is further known to provide a plurality of sensors associated with the respective mechanisms for providing input information to the respective motor controllers. The motor controllers are programmed to function independently of the other motor controllers. That is, there is a minimum of inter-controller communication generally restricted to "trip" and output speed information.
Synchronization can be achieved through the use of trip information and/or envelope speed information communicated between the several motor controllers. For example, the mailing machine transport motor controller upon receiving a trip signal and existing speed information from the proceeding process station, e.g., a scale, can initiate a count down to arrival of the envelope from the proceeding station. Further, the mailing machine transport motor controller can initiate transport speed adjustment to match the speed of the incoming envelope.
Such mail processing systems as afore-described have required the use of multiple microprocessor motor controllers, each of which controllers must be programmed. The programming of each controller is generally dependent on the hardware configuration of the mail processing system. Changes in the hardware configuration, such as, the addition of a scale, generally require program changes to the downstream controllers.